In recent years, multimedia communications over the Internet and other wired and/or wireless communications networks have gained increased popularity. Such multimedia communications can involve multiple participant devices performing various functions including encoding, decoding, and/or transcoding video and/or audio data streams generated by the respective participant devices. In such multimedia communications, successful transmissions of multimedia data between the participant devices over packet communications networks generally require sufficient bandwidth and low latency for minimal packet loss. Such transmissions of multimedia data are typically based on the real-time transport protocol (RTP), and the delivery of such multimedia data is typically monitored using the real-time transport control protocol (RTCP).
For example, a first participant device that receives multimedia data (such a first participant device also referred to herein as a/the “receiving participant device”) in the form of RTP packets can provide packet loss feedback information to a second participant device that transmitted the multimedia data (such a second participant device also referred to herein as a/the “transmitting participant device”) in one or more RTCP feedback packets. Such packet loss feedback information can take the form of a General Negative Acknowledgment (GNACK) message or a Picture Loss Indication (PLI) message. The receiving participant device can provide such a GNACK message to the transmitting participant device to identify a specific packet(s) that has/have been detected as being lost or missing, and to request the transmitting participant device to retransmit the lost or missing packet(s). Further, the receiving participant device can provide such a PLI message to the transmitting participant device to indicate the loss of an unspecified amount of packets, and to request the transmitting participant device to transmit an intra-coded video frame (such an intra-coded video frame also referred to herein as an/the “intra-frame” or “I-frame”).
Multimedia communications can be problematic, however, particularly when transmissions of multimedia data are performed over public communications networks such as the Internet. For example, while engaging in multimedia communications over the Internet, various participant devices may be subjected to different levels of network congestion, which can result in reduced bandwidth, increased latency, and ultimately increased packet losses, which can severely degrade the multimedia quality of experience (QoE), or, more particularly, the video QoE, of participant users. The loss of one or more video packets at a receiving participant device can result in video QoE degradation that can persist until the next complete I-frame is received at the receiving participant device for decoding.
Moreover, conventional approaches that employ RTCP feedback packets for providing packet loss feedback information to request the retransmission of one or more lost or missing video packets, or the transmission of one or more I-frames, have frequently been incapable of achieving levels of video QoE generally desired and/or required for today's multimedia communications. For example, such conventional approaches of providing packet loss feedback information to a transmitting participant device can result in the generation of redundant requests for retransmission of lost or missing video packets and/or for transmission of I-frames, which can have a detrimental effect on the available bandwidth and exacerbate the problem of video QoE degradation.
It would therefore be desirable to have improved systems and methods of providing packet loss feedback information in multimedia communications that avoid at least some of the problems associated with such conventional approaches described herein.